1. Field of the Invention
The present invention relates to a recording/reproducing head for a dielectric recording medium, for recording information in microdomains in a dielectric substance of the dielectric recording medium and for reproducing information recorded in the dielectric recording medium, and relates to a method of producing the recording/reproducing head.
2. Description of the Related Art
As high-density, large-capacity recording/reproducing apparatuses of randomly accessible type, there are known an optical disk apparatus and a hard disc drive (HDD) apparatus. Moreover, a recording/reproducing technique using a scanning nonlinear dielectric microscopy (SNDM) for the nanoscale analysis of a dielectric (ferroelectric) material has been recently proposed by the inventors of the present invention.
In optical recording, an optical pickup with a laser as a light source is used. Data is recorded by forming pits that are concavo-convex on a disk surface or forming the crystal phase of a phase shift recording medium. The data is reproduced by using the difference in the reflectance of amorphous phases or using the magneto optical effect. However, the pickup is large and is not appropriate for high-speed reading, and the size of the recording pit is defined by the diffraction limit of light, so that its recording density is limited to 50 G bit/inch2.
In the longitudinal recording of magnetic recording as represented by the HDD, a magnetic resistance (MR) head has been recently realized using giant magnetic resistance (GMR). In addition, perpendicular magnetic recording is used. Therefore, its recording density is expected to be larger than that of the optical disk by using. However, the recording density is limited to 1 T bit/inch2 due to thermal fluctuation of magnetic recording information and the presence of a Bloch wall in a code reverse or sign change portion, even if patterned media are used considering the above cause.
Using the SNDM to measure a non-linear dielectric constant of a ferroelectric material, it is possible to detect the plus and minus of a ferroelectric domain. Moreover, the SNDM is found to have sub-nanometer resolution using an electrically conductive cantilever (or probe) which is used for an atomic force microscopy (AFM) or the like and which is provided with a small probe on its tip portion. In the SNDM, a resonance circuit is formed with the probe, an inductor, an oscillator connected with the probe, a capacitance of the dielectric (ferroelectric) material just under the probe and a return electrode which is placed near the tip portion of the probe. The return electrode is an electrode for returning an alternating electric field from the tip portion of the probe through the dielectric (ferroelectric) material. The conventional SNDM is designed to be an analysis apparatus. The return electrode used in this apparatus is a metal conductor of a ring shape of 7 mm outer diameter, 3 mm inner diameter and about 0.5 mm thickness, and it is placed so as to surround the tip portion of the probe.
However, the above-described SNDM has not been specially developed in view of a recording/reproducing apparatus and thus have such a problem that the probe is large or that assembling is complicated. Moreover, if it has a plurality of probes in order to increase a data transfer rate, the complication increases more.